SecDef Gates has ordered 1,200 Marines into the Mediterranean by way way of the USS Ponce and USS Kearsage. Gates says the ships are, for the moment, there for the purposes of evacuation and humanitarian relief contingencies. From a defense Q&A:

Q: Mr. Secretary, Admiral Mullen just mentioned that in Libya Moammar Gadhafi is waging war on his own people, as you put it. What — is U.S. military intervention realistic? And what specific kinds of options are you considering? Could you describe, for example, the possibility of a no-fly zone or arming rebel forces?
SEC. GATES: Well, first of all, I have directed several Navy ships to the Mediterranean. The USS Kearsarge and the [USS] Ponce will be entering the Mediterranean shortly and will provide us a capability for both emergency evacuations and also for humanitarian relief.
About 1,400 Marines from the Kearsarge are serving in Afghanistan. And so we are sending about 400 Marines from the U.S. that will be in support of the Kearsarge’s mission.
So those are the actions that we have taken at this point. We’re obviously looking at a lot of options and contingencies. No decisions have been made on any other actions.
I would — I would note that the U.N. Security Council resolution provides no authorization for the use of armed force. There is no unanimity within NATO for the use of armed force. And the kinds of options that have been talked about in the press and elsewhere also have their own consequences and second- and third-order effects. So they need to be considered very carefully.
Our job is to give the president the broadest possible decision space and options, and to go into the things that we’re thinking about, the options that we’re providing, I think, have the potential to narrow his decision space. And I have no intention of doing that.